The candidate is a junior investigator in pediatric rheumatology with advance training in clinical epidemiology and a research focus on pharmacoepidemiology and comparative effectiveness of chronic rheumatic disease, including enthesitis-related arthritis (ERA), which is a category of juvenile idiopathic arthritis (JIA). The candidate proposes a comprehensive interdisciplinary program that will provide her with the skills and experience for her development into an independent clinical investigator in pediatric rheumatology. Her career development will be guided by a comprehensive group of co-investigators with a long history of productive collaboration. The project will build upon the foundations of pharmacoepidemiology and clinical epidemiology research knowledge that she obtained during her MSCE training and thesis work and will prepare her to conduct intervention studies in children with all forms of JIA. JIA is the most common rheumatologic condition in childhood, affecting 1 to 4 per 1,000 children. ERA is a JIA category that accounts for 10-20% of JIA. Physicians treat ERA to control inflammation and to prevent morbidities such as chronic uveitis, growth disturbance, contracture, joint destruction, and functional limitation. A subset of children with ERA will progress to ankylosing spondylitis (AS), a condition characterized by spinal and back pain, stiffness, and eventual fusion of the vertebra. Observational studies suggest that less than 20% of children with ERA achieve remission within five years after diagnosis. Significant challenges to providing and studying ERA treatment today are limited by methods for assessing enthesitis, disease activity, and response to therapy. The proposed plan of research addresses these challenges and will (1) evaluate the accuracy of physical examination to detect enthesitis, (2) develop and validate a composite ERA disease activity index, and (3) compare the effectiveness and safety of alternative treatment strategies in incident cases of ERA. This research will provide the preliminary data, hypotheses, and outcome measures for future safety, efficacy, and cost- effectiveness studies of ERA treatment algorithms.